Manufacture of cutting-tools and tool-blanks



Ihvrrnn STATES PATENT OFFICE.

MARTIN A. HOWELL, JR, OF CHICAGO, ILLINOIS.

MANUFACTURE OF CUTTING-TOOLS AND TOOL-BLANKS.

SPECIFICATION forming part of Letters Patent No. 310,280, dated January 6, 1885.

Application filed March 28, 1884. (No specimens.)

To all whom, it may concern:

Be it known that I, MARTIN A. HOWELL, J r. a citizen of the United States, residing at Ohicago, in the county of Cook and State of Illinois, have invented new and useful Improvements in Manufacture of Cutting-Tools and Tool-Blanks-such as Files, Taps. Dies, &c. of which the following is a specification.

This invention relates to improvements in the manufacture of tool-blanks and tools, such as files, taps, dies, and other cutting implements; and it has for its object to increase the standard of such blanks or tools made from low-carbon, granular, or homogeneous metals, while decreasing the cost of production.

In carrying out my invention I cut the blanks from bars or sheets rolled from railwaybars, old rails, cropends, or ingots of Bessemer or other similar metal, which is of low carbon, granular, and similar in its character to castiron. The blanks, having been properly cut or surfaced by any of the usual processes for accomplishing such object, are placed in a flask or retort, which is capable of being hermetically sealed, to effectually exclude the external atmosphere and prevent leakage from within. The flask or retort charged and sealed is placed in the mufi'le of a furnace, and detachably connected by a pipe with a reservoir or gas-holder containing, preferably, pure hydrocarbon Vapor under pressure, which is driven into the flask and from through a vent-cock, until, by the flame at the vent-cock, the evidence of the purity of the vapor and its freedom from oxygen is assured, when the cock is closed and the files held in an atmosphere of pure hydrocarbon vapor until a high annealing-heat is reached. The pressure is now increased at the reservoir or gas-holder until the operation of carburation is completed, which, at the proper heat, can be effected in one hour. The flask is then disconnected from the reservoir or gas-holder, sealed by closing the inlet to the same, and withdrawn from the muffle and permitted to cool with the contents enveloped in the carbureting vapor, the flask not being opened until the contents are cold. By this means the blanks or tools are retained at a high annealing heat in a carbureting atmosphere entirely free from oxygen to the end of the heating and subsequent cooling process, and

expels all air there-- the metal is carbureted and restored to its true character, exhibiting the characteristics of a true carbide or carburet. The blanks or tools thus restored to a standard of extreme durability are now hardened and tempered in the usual manner. I have employed vaporized alkaline or'basie salts-such, for example, as the carbonates or chlorates of ammonia or potash, the bichromates, the cyanuret, or form-cyanide of potassium, either singly or in combination with chloride of sodium, and many other well-known agents, many of which are dangerous of inhalation, expensive, and uncertain and irregular in the results obtained therefrom. For a spongy granular metal heated to the proper degree I find no agent so regular and decisive and none so practically inexpensive as a pure va por of hydrocarbon, through the aflinity said heated metal displays for this alloy. The structure of Bessemer'metal, such as is used in the manufacture of railway bars or rails, is granular and similar in its character to castiron, and when heated to a sufficient degree below fusion becomes extremely spongy or porous, and is easily penetrated by carbon under pressure. hen such metal is cement-ed with carbon in retorts freed from oxygen, as above set forth, until said metal is cool, a pure carbon steel of great resistance is obtained, thus enabling me to considerably reduce the cost of producing steel eutting'tools of great tenacity and high standard qualities. If the metal alluded to is fibrous or puddled caststeel, the resistance offered to the penetration or saturation of the carbon-vapor is so prolonged as to render the manufacture of files or other cutting-tools unnecessarily expensive as compared with themanufacture from the granular metal. The crop-ends, old rails, or ingots of Bessemer metal are too low in carbon to be used practically for any purpose when a steel of high carbon is necessary; By my invention I utilize such waste products of old rails or ingots of Bessemer metal in producing tool-blanks or tools of a high standard and great tenacity by means comparatively inexpensive, thereby giving to the public a better article at a price far below that of common cast-steel of commerce.

In the Letters Patent No. 273,536, issued to me March 6, 1883, is set forth a process for converting file-blanks made from decarburized cast-iron, the blanks being first cast in sand molds, then decarburized, ground, and cut, the object being to secure the metal in a granular condition, in order to saturate it perfectly by the process. It has been found by me that in casting such blanks there is great liability to imperfections from sand-holes, cracks, and similar things, and the waste is a prominent objection in connection with the cost of decarburizing, all of which increases the cost beyond a reasonable limit.

The production of cast-iron blanks set forth in my Letters Patent alluded to is obj ectionable in a measure, owing to the impossibility of obtaining perfect or good results, as regards quality of the product, in comparison to steel; but by operating in the manner set forth on blanks cut from rolled bars of homogeneous or Bessemer metal of a granular character, in all respects similar to cast-iron, but perfect in structure, the result is not only perfect and less expensive than annealed castings, but I produce a perfect article at less than one-half the cost of the cast-iron blanks, and, besides, the finished article or product is superior through the absence of impurities common to all castings by the ordinary method of sandmolding and cementation in oxides. \Vhen the metal is granular-such as cast-iron or Bessemer metal-it becomes spongy and porous when heated, and takes the carbon with rapidity and without blisters, as with fibrous metal.

I do not claim decarburizing cast iron blanks and then recarburizing them in a hermetically-sealed flask, as in my Letters Pat ent alluded to; nor do I claim passing heated carbon containing gases over heated bars of malleable iron in permanent or fixed retorts of clay or fire-bricks, and then withdrawing the bars while hot for converting the iron into steel; nor as claiming annealing horseshoe i nail blanks by inclosin g oiled blanks, or blanks in oil, in a retort, subjecting them to a cherryred heat, and volatilizing the oil and cooling the blanks in the retort, as such are not my invention. 1 Having thus described my invention, what I claim is 1 In the manufacture of tools, implements, or other products of steel, the process which consists in the rolling or cutting of the soft blanks i from decarburized iron or low-carbon steels of made by the Bessemer or similar processesand the restoration thereof to a true carburet in a scaled fiask connected with a gas-holder containing the vapors of hydrocarbon or its equivalent, said vapor being freed from oxygen and kept under pressure during the process of carbureting, and held free from oxygen to the end of the cooling or discharge of the contents of said flask.

In testimony whereof I have hereunto set my hand in the presence of two subscribing witnesses.

lllAltTlN A. HOWELL, JR.

\Vitnesses:

THOMAS II. HOWELL, WILsoN S. HownLL.

l l 1 l granular or semi-granular structureas that 

